A system structure of SAE according to the related art is illustrated in FIG. 1. The system structure of system architecture evolution (SAE) in FIG. 1 is described as following.
User Equipment 101 (hereinafter referred to as UE) is a terminal device used to receive data. 102 EUTRAN, also called ENB, is a radio access network of the LTE SAE, for providing interface through which an LTE mobile station accesses the radio network. Through interface S1, EUTRAN connects to a mobility management entity (MME) 103 and a user plane entity serving gateway (S-GW) 104 in the mobile station. MME 103 is adapted for managing mobile context, session context for the UE, and holding user information on security. S-GW 104 primarily provides a function of user plane. An interface S1-MME is adapted for establishing radio access bearer, forwarding messages from UE to MME through a wireless access network. The combination of MME 103 and S-GW 104 is similar to the original serving general packet radio service (GPRS) support node (SGSN) 106. It is possible that both MME and S-GW locate at the same physical entity. Packet data network (PDN) Gateway 105 is adapted for the functions like accounting, legally monitoring, etc. And it is possible that both the S-GW and the PDN Gateway locate at the same physical entity. SGSN 106 provides routing for data transmission in existing universal mobile telecommunications system (UMTS). An existing SGSN finds a corresponding gateway GPRS supporting node (GGSN) according to an access point name (APN). HSS 107 is a home subscription sub-system for the UE and is adapted for storing user information such as the current location of UE, address of the serving node, security information on the user, activated packet data protocol (PDP) context for the UE and so on. Policy and charging rules function (PCRF) 108 provides quality of service (QoS) policy and accounting rules through interface S7.
In general, a user data stream reaches the S-GW 104 through PDN Gateway 105. Then, through the GPRS tunnel protocol (GTP) channel, data is sent by the S-GW to the ENB where the UE locates in, and now it is sent by the ENB to corresponding UE.
HNB refers to a Node B applied in a home. It also can be applied in such site as a university, a company and so on. HNB is a plug and play device. Difference between an HNB and a general macro node B is that: in general not all user equipments (UEs) can access an HNB. For example, only the UEs in a user's home or that are allowed to access the HNB can access the corresponding HNB. And for the HNB in a company, only the company's staff and its allowed partners can access the HNB. The HNB group (e.g., the HNB in a company) bearing the same access subscriber cluster is called closed subscriber group (CSG). No interface X2 (interface between Node Bs in SAE) exists between general HNBs (e.g., the HNBs in homes) or between an HNB and a macro Node B. Through interface S1, a UE switches between HNBs or between an HNB and a macro Node B.
For an HNB applied in a company or university or the like, a UE frequently moves between two HNBs in the same company. In this case, the switch is always implemented through interface S1 so that great delay causes and efficiency is very poor. In addition, information such as radio resource management and so on cannot be exchanged between two HNBs in the same company so that resources cannot be utilized effectively.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.